Cylinder head

ABSTRACT

A cooling water pipe is deformed so as to have outlet openings respectively placed in a position around a fuel injection nozzle and in a position between ports, and the cooling water pipe is inserted to be placed inside the cylinder head. Thereby, the position around the fuel injection nozzle and the position between the ports can be simultaneously and efficiently cooled, and the structure becomes simpler and the production becomes easier. In order to deform the cooling water pipe, for example, the cooling water pipe is bent first, and subsequently bulge forming by hydraulic pressure is performed. Preferably, the cooling water pipe is made of aluminum. Thereby, the cooling water pipe becomes easier to melt into when the cylinder head is cast.

TECHNICAL FIELD

This invention relates to a cylinder head of an internal combustionengine, and in particular, a cylinder head of an internal combustionengine in which both a position around a fuel injection nozzle and aposition between ports can be simultaneously and efficiently cooled.

BACKGROUND ART

FIG. 5 is a sectional view of a conventional cylinder head. In FIG. 5,101 is a hole for attachment of a fuel injection nozzle, 102 is anintake port, 103 is an exhaust port, and 104 is a water jacket. As shownin FIG. 5, a position around the fuel injection nozzle and a positionbetween ports are cooled by cooling water in the water jacket 104. Inthe cylinder head shown in FIG. 5, the cooling water which flows intothe cylinder head from the cylinder block (not shown) is made to flowinto one big room (water jacket 104). Consequently, the flow velocity ofthe cooling water in the water jacket 104 becomes relatively slow(approximately 1 m/sec). It is no problem if the cylinder head shown inFIG. 5 is applied to a relatively low-power engine. However, if thecylinder head shown in FIG. 5 is applied to a relatively high-powerengine, it is possible that cooling performance lacks and the cylinderhead cracks by temperature rise at the lower surface of the cylinderhead.

In order to solve this problem, such a cylinder head is known that thewater jacket is divided into two, one of which is in a lower surfaceside of the cylinder head and another of which is in an upper surfaceside of the cylinder head. There is an example of this kind of cylinderhead that is described in Japanese laid-open Patent Application No.2000-34950. FIG. 6 is a sectional view of the cylinder head having thewater jacket divided into the lower surface side of the cylinder headand the upper surface side of the cylinder head. In FIG. 6, 201 is ahole for attachment of the fuel injection nozzle, 202 is an intake port,203 is an exhaust port, 204 is a water jacket in the lower surface sideof the cylinder head, and 205 is a water jacket in the upper surfaceside of the cylinder head. In the cylinder head shown in FIG. 6, in viewof point that the lower side of the cylinder head is more necessary tobe cooled than the upper side of the cylinder head, the cross-sectionalarea of the water jacket 204 in the lower surface side of the cylinderhead is made relatively small, and the cross-sectional area of the waterjacket 205 in the upper surface side of the cylinder head is maderelatively large. That is, the flow velocity of the cooling water in thewater jacket 204 in the lower surface side of the cylinder head ishigher than the flow velocity of the cooling water in the water jacket205 in the upper surface side of the cylinder head. The flow velocity ofthe cooling water in the water jacket 205 in the lower surface side ofthe cylinder head becomes approximately 3 m/sec. Therefore, the lowersurface side of the cylinder head can be efficiently cooled.

Also in the cylinder head in which the lower surface side can beefficiently cooled, it is known that it is more necessary to cool a sidenear the fuel injection nozzle than a side apart from the fuel injectionnozzle among the circumference of the port. FIG. 7 is a perspective viewof an example of the water jacket in the lower surface side of thecylinder head. In FIG. 7, 301 is a fuel injection nozzle part and 302 isa port part. The cooling water flows inside the water jacket in thelower surface side of the cylinder head as shown by arrow in the figure.In the water jacket in the lower surface side of the cylinder head shownin FIG. 7, in view of point that the side near the fuel injection nozzlepart 301 is more necessary to be cooled than the side apart from thefuel injection nozzle part 301 among the circumference of the port, thecross sectional area of the water jacket which is in the side apart fromthe fuel injection nozzle part 301 (part A in the figure) among thecircumference of the port part 302 is reduced so that the cooling wateris hard to flow in the side apart from the fuel injection nozzle part301 among the circumference of the port part 302. However, to reduce thecross sectional area of the water jacket means to make the crosssectional area of the sand core used for casting of the cylinder headsmall. Therefore, it is possible that the core breaks when set beforethe casting of the cylinder head, and that the core is damaged by thepressure of the molten metal during the casting.

In order to solve this problem, traditionally, such a cylinder head isknown that a cooling water pipe as a cooling water passage is locatedinside of the cylinder head. There is an example of this kind of thecylinder head that is described in Japanese laid-open Patent ApplicationNo. 2000-170600. In the cylinder head described in the Japaneselaid-open Patent Application No. 2000-170600, a cooling water passage isformed around the exhaust port. In detail, the cooling water passage isformed inside each exhaust valve seat. The cooling water passages whichare respectively around a pair of exhaust ports being next to each otherare communicated with each other by a pipe. An outlet opening is formedin the pipe, and the cooling water flowing into the pipe from thecooling water passage in the exhaust valve seat is discharged outside ofthe pipe through the outlet opening. That is, the cooling water in thepipe is discharged toward a position between the pair of adjoiningexhaust ports.

However, in the cylinder head described in the Japanese laid-open PatentApplication 2000-170600, no outlet opening of the pipe for the coolingwater is provided around the fuel injection nozzle, although break ordamage of the core when casting of the cylinder head are avoided sincethe cooling water pipe as a cooling water passage is placed inside thecylinder head. Therefore, in the cylinder head described in the Japaneselaid-open Patent Application 2000-170600, a position around the fuelinjection nozzle and a position between ports cannot be efficiently,simultaneously cooled.

And also, in the cylinder head described in the Japanese laid-openPatent Application 2000-170600, one cooling water pipe is necessary tocool the position between the pair of adjoining ports. That is, two ormore cooling water pipes are necessary to cool each position betweeneach pair of adjoining ports among a plurality of pairs of adjoiningports. That is, in the case that there are two exhaust ports and twointake ports in one cylinder, and that the position between the pair ofadjoining exhaust ports and the position between the exhaust port andthe intake port which adjoin each other intend to be cooled, a pluralityof cooling water pipes are required. Therefore, the structure of thecylinder head will become complicated and the casting process of thecylinder head will become complicated.

Therefore, it is an object of this invention to provide a cylinder headin which the position around the fuel injection nozzle and the positionbetween ports can be efficiently and simultaneously cooled, and thestructure of which is simpler and the production of which is easier thanthe cylinder head described in the Japanese laid-open Patent Application2000-170600.

DISCLOSURE OF INVENTION

An invention concerning claim 1 of this application is a cylinder headhaving a cooling water pipe inside, wherein the cooling water pipe isinserted and has outlet openings respectively placed in a positionaround a fuel injection nozzle and in a position between ports.

In this cylinder head, the outlet openings of the cooling water pipe arerespectively placed in the position around the fuel injection nozzle andin the position between the ports. Therefore, unlike the cylinder headdescribed in the Japanese laid-open Patent Application 2000-170600 inwhich no outlet opening of the cooling water pipe is placed in theposition around the fuel injection nozzle, the position around the fuelinjection nozzle and the position between the ports can besimultaneously and efficiently cooled. Furthermore, the cooling waterpipe is deformed such that the cooling water pipe has the outletopenings respectively placed in the position around the fuel injectionnozzle and in the position between the ports. That is, the cooling waterpipe deformed extends through the position around the fuel injectionnozzle and the position between the ports. Therefore, providing thecooling water pipe with the outlet openings which are respectivelyplaced between respective pairs of adjoining ports for example, it ispossible for one cooling water pipe to cool not only the positionbetween a pair of adjoining exhaust ports but also the position betweenthe exhaust port and the intake port adjoining each other. That is, thestructure becomes simpler and thus the production becomes easier thanthe cylinder head described in the Japanese laid-open Patent Application2000-170600 which requires two or more cooling water pipes to cool eachposition between adjoining ports of two or more pairs of ports.

As described above, according to the invention as defined in claim 1,unlike the cylinder head described in the Japanese laid-open PatentApplication 2000-170600 in which no outlet opening of the cooling waterpipe is provided in the position around the fuel injection nozzle, theposition around the fuel injection nozzle and the position between theports can be simultaneously and efficiently cooled. Furthermore,providing the cooling water pipe with the outlet openings which arerespectively placed between respective pairs of the adjoining ports forexample, it is possible for one cooling water pipe to cool not only theposition between a pair of adjoining exhaust ports but also the positionbetween the exhaust port and the intake port adjoining each other. Thatis, the structure becomes simpler and thus the production becomes easierthan the cylinder head described in the Japanese laid-open PatentApplication 2000-170600 which requires two or more cooling water pipesto cool each position between adjoining ports of two or more pairs ofports.

Moreover, an invention concerning claim 2 is such that the cooling waterpipe extends from an inlet opening to the outlet opening without passingthrough a valve seat.

As mentioned above, in the cylinder head described in the Japaneselaid-open Patent Application 2000-170600, the cooling water passage isdefined in the valve seat and the cooling water pipe is extendedtherefrom. Therefore, in the valve seat of the cylinder head describedin the Japanese laid-open Patent Application 2000-170600, a positioningfor precisely fitting with the valve and a positioning for preciselyfitting with the cooling water pipe are necessary. That is, in thecylinder head described in the Japanese laid-open Patent Application2000-170600, there is a possibility that the valve does not preciselysit on the valve seat if it is intended to prevent a leak of the coolingwater from a connection part between the valve seat and the coolingwater pipe. In view of this problem, in the cylinder head as defined inclaim 2, the cooling water pipe extends from the inlet opening to theoutlet opening without passing through the valve seat. Therefore, theproblem involved in the cylinder head described in the Japaneselaid-open Patent Application 2000-170600 can be avoided.

As described above, according to the invention as defined in claim 2,the problem involved in the cylinder head described in the Japaneselaid-open Patent Application 2000-170600 that the positioning forprecisely fitting with the valve and the positioning for preciselyfitting with the cooling water pipe are required for the valve seat canbe avoided.

Moreover, an invention as defined in claim 3 is such that the coolingwater pipe is made of aluminum.

In the cylinder head as defined in claim 3, the cooling water pipe madeof aluminum is inserted in the cylinder head. Therefore, compared withthe case that the cooling water pipe made of another material isinserted, the cooling water pipe easily melts into the cylinder head.That is, it can be prevented that the cooling water pipe inserteddissociates from the cylinder head.

More specifically, the cooling water pipe deformed is inserted in a partof the cooling water passage which is necessary to be cooled most butonly has a relatively small cross sectional area of the cooling waterpassage. Thereby, the cross sectional area of the cooling water passageis secured, and it is avoided that the core is broken or damaged whenthe cylinder head is cast. When the cylinder head is cast, the coolingwater pipe into which sand is filled is set, and subsequently the sandis filled in the mold for making the cooling water passage (waterjacket).

Preferably, the sand in the cooling water pipe collapses during heatprocess to be removed, for example. Moreover, in order to deform thecooling water pipe, the cooling water pipe is bent first and then abulge forming is performed by hydraulic pressure etc.

As described above, according to the invention as defined in claim 3,the cooling water pipe easily melts into the cylinder head, comparedwith the case that the cooling water pipe made of another material isinserted. That is, it can be prevented that the cooling water pipeinserted dissociates from the cylinder head.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing a structure of one embodiment of acylinder head of this invention.

FIG. 2 is a plan view of the cooling water pipe shown in FIG. 1.

FIG. 3 is a front elevation view of the cooling water pipe shown in FIG.1.

FIG. 4 is a sectional view taken along a line IV-IV of FIG. 1.

FIG. 5 is a sectional view of the conventional cylinder head.

FIG. 6 is a sectional view of the cylinder head in which the waterjacket is divided into one part in the lower surface side of thecylinder head and another part in the upper surface side of the cylinderhead.

FIG. 7 is a perspective view of an example of the water jacket in thelower surface side of the cylinder head.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of this invention will now be described with reference toaccompanying drawings.

In FIG. 1-4, 1 is a cooling water pipe, 2 is a fuel injection nozzle, 3is a port, 4 is an outlet opening placed in a position between ports forcooling the position between the ports, and 5 and 6 are outlet openingsplaced in a position around the fuel injection nozzle 2 for cooling theposition around the fuel injection nozzle. 7 and 8 are inlet openingsfor supplying cooling water to the outlet openings 4, 5 and 6. 9 is ahole for attachment of the fuel injection nozzle, and 10 is a valve seatinsert.

As shown in FIGS. 1 and 4, in the cylinder head of this embodiment, thecooling water pipe 1 is inserted (or cast in or embedded) to be placedinside the cylinder head. Moreover, one cooling water pipe 1 is placedper cylinder. The cooling water pipe 1 is provided with the inletopenings 7 and 8 for supplying the cooling water into the cooling waterpipe 1, and the outlet openings 4, 5, and 6 for discharging the coolingwater out of the cooling water pipe 1. The cooling water pipe 1 isdeformed into a bent form such that the position between the ports 3 canbe cooled by the cooling water discharged from the outlet opening 4 andthat the position around the fuel injection nozzle 2 can be cooled bythe cooling water discharged from the outlet openings 5 and 6. In orderto deform the cooling water pipe 1 as shown in FIGS. 2 and 3, thecooling water pipe with a straight form is bent first, and subsequently,a bulge forming with a hydraulic pressure etc. is performed.

As shown in FIGS. 1-3, the cooling water sent from the cylinder block(not shown) is supplied into the cooling water pipe 1 through the inletopenings 7 and 8. A part of the cooling water is discharged from theoutlet opening 4 to the position between the ports 3, and the positionbetween the ports 3 is cooled by the cooling water. And also, anotherpart of the cooling water supplied into the cooling water pipe 1 isdischarged from the outlet openings 5 and 6 to the position around thefuel injection nozzle 2, and the position around the fuel injectionnozzle 2 is cooled by the cooling water.

When the cylinder head of this embodiment is cast, firstly the coolingwater pipe 1 filled with sand is set in a mold. Positioning of thecooling water pipe 1 is carried out by portions respectively having theinlet openings 7 and 8 (refer to FIG. 3). That is, in the cooling waterpipe 1 of this embodiment, the portions in which the inlet openings 7and 8 are respectively provided serve as the portions for positioningthe cooling water pipe 1 when casting. Subsequently, the sand is filledfor making the other part of the cooling water passage than the coolingwater pipe 1. The sand inside the cooling water pipe 1 collapses duringa heat process to be removed. That is, in the cylinder head of thisembodiment, the cooling water pipe deformed is inserted in such a partof the cooling water passage that is most necessary to be cooled butonly has a relatively small cross sectional area of the cooling waterpassage. Thereby, the cross sectional area of the cooling water passageis secured, and it is avoided that the core is broken or damaged whenthe cylinder head is cast.

The cooling water pipe 1 of this embodiment is made of aluminum.Accordingly, the cooling water pipe 1 easily melts into the cylinderhead when the cylinder head (which is made of material such as aluminumalloy) is cast. However, in another embodiment, it is also possible tomake the cooling water pipe by using material other than aluminum.

As described above, according to this embodiment, the outlet opening 4of the cooling water pipe 1 is placed in the position around the fuelinjection nozzle 2, and the outlet openings 5 and 6 of the cooling waterpipe 1 are placed in the position between the ports 3. Therefore, unlikethe cylinder head described in the Japanese laid-open Patent Application2000-170600 in which the outlet opening of the cooling water pipe is notplaced in the position around the fuel injection nozzle, the positionaround the fuel injection nozzle 2 and the position between the ports 3can be simultaneously and efficiently cooled. Furthermore, according tothis embodiment, one bent cooling water pipe 1 per cylinder is insertedwhich is deformed so as to have the outlet openings 4, 5 and 6respectively placed in the position around the fuel injection nozzle 2and the position between the port 3. Therefore, the structure becomessimpler and thus the production becomes easier than the cylinder headdescribed in the Japanese laid-open Patent Application 2000-170600 whichrequires two or more cooling water pipes per cylinder to cool eachposition between adjoining ports of two or more pairs of ports.

This application claims priority benefits of Japanese Patent ApplicationNo. 2002-109077, filed on Apr. 11, 2002, and the content of which isherein incorporated by reference.

Industrial Applicability

This invention can be widely applied to an engine such as a diesel orgasoline engine of a water cooled type.

1. A cylinder head having a cooling water pipe inside, wherein thecooling water pipe is inserted and has outlet openings respectivelyplaced in a position around a fuel injection nozzle and in a positionbetween ports.
 2. The cylinder head as defined in claim 1, wherein thecooling water pipe extends from an inlet opening to the outlet openingwithout passing through a valve seat.
 3. The cylinder head as defined inclaim 1, wherein the cooling water pipe is made of aluminum.
 4. Thecylinder head as defined in claim 3, wherein material of the cylinderhead is aluminum alloy.
 5. The cylinder head as defined in claim 1,wherein the cylinder head has one cooling water pipe per cylinder. 6.The cylinder head as defined in claim 5, wherein the cooling water pipecomprises one section extending from one side of the cylinder head to aposition near the fuel injection nozzle, and another section extendingfrom another side of the cylinder head to a position near the fuelinjection nozzle, the one section has one inlet opening for introducingcooling water at its end located in the one side of the cylinder head,and has one first outlet opening for discharging the cooling water tothe position around the fuel injection nozzle and one second outletopening for discharging the cooling water to the position between theports at its end located near the fuel injection nozzle, and the anothersection has another inlet opening for introducing the cooling water atits end located in the another side of the cylinder head, and hasanother first outlet opening for discharging the cooling water to theposition around the fuel injection nozzle and another second outletopening for discharging the cooling water to the position between theports at its end located near the fuel injection nozzle.
 7. The cylinderhead as defined in claim 6, wherein the one second outlet opening andthe another second outlet opening are integrally formed with each other,and the one first outlet opening and the another first outlet openingare separately formed from each other.
 8. The cylinder head as definedin claim 6, wherein four ports are provided per cylinder and arearranged such that each of the ports is in each corner of square, thefuel injection nozzle is placed in an approximate middle position of thefour ports, the one section of the cooling water pipe is placed betweentwo ports among the four ports, and the another section of the coolingwater pipe is placed between another two ports among the four ports. 9.The cylinder head as defined in claim 6, wherein the ends of the onesection and the another section of the water cooling pipe which arelocated near the fuel injection nozzle are formed such that theygenerally surrounds the fuel injection nozzle.
 10. A cylinder headcomprising: four ports arranged such that each of the ports is in eachcorner of square; a fuel injection nozzle placed in an approximatemiddle position of the four ports; and a cooling water pipe havingoutlet openings respectively placed in a position around a fuelinjection nozzle and in a position between the ports: wherein thecooling water pipe comprises one section extending from one side of thecylinder head to a position near the fuel injection nozzle through aposition between two ports among the four ports, and another sectionextending from another side of the cylinder head to a position near thefuel injection nozzle through a position between another two ports amongthe four ports, the one section has one inlet opening for introducingcooling water at its end located in the one side of the cylinder head,and has one first outlet opening for discharging the cooling water tothe position around the fuel injection nozzle and one second outletopening for discharging the cooling water to the position between theports at its end located near the fuel injection nozzle, and the anothersection has another inlet opening for introducing the cooling water atits end located in the another side of the cylinder head, and hasanother first outlet opening for discharging the cooling water to theposition around the fuel injection nozzle and another second outletopening for discharging the cooling water to the position between theports at its end located near the fuel injection nozzle.
 11. Thecylinder head as defined in claim 10, wherein the one second outletopening and the another second outlet opening are integrally formed witheach other, and the one first outlet opening and the another firstoutlet opening are separately formed from each other.
 12. The cylinderhead as defined in claim 11, wherein the ends of the one section and theanother section of the water cooling pipe which are located near thefuel injection nozzle are formed such that they generally surrounds thefuel injection nozzle.
 13. The cylinder head as defined in claim 12,wherein a position of the one inlet opening of the one section and aposition of the another inlet opening of the another section are differfrom each other in a longitudinal direction of the cylinder head.